Printed only the thumbwheels for my Chinese i3, they fit perfectly! Just big enough to have some clearance of the mount plate to turn them but not too big to be in the way of print bed movement. Heated up the nuts to insert them. Thanks for the design!

When printing with 100% infill, there is no place for flex when press-fitting the nut.I recommend 25% infill, as this will make a strong part.
Others has suggested heating the nut up to make a perfect fit.

I'm basically using a similar mod. Just without the washer and without the spring cup. So if you don't want to print them: they're not a must. It'll just work with the stock parts + thumbnut + regular nut to fix the screw onto the hotbed.

I printed these out over the weekend and the following tip might help if you use PLA.
After printing, I used a pair of long nosed radio pliers to squeeze the nut partially into the thumbwheel. However, this had the effect of warping the thumbwheels somewhat. What I did was to put some boiling water in to a jug and then drop the thumbwheels in the water for a couple of minutes. PLA goes pliable in hot water, so after a couple of minutes I quickly removed each disk (the radio pliers are handy here!) and swiftly squeezed them in a vice to flatten them out and cool them down. You have to be really quick here, as the PLA starts to harden again within 10 seconds or so of removing from the water. Once removed, you'll have a flat thumbwheel and the nut nicely squeezed into the centre.

The reason for the washer is to protect the heat bed from the end of the spring and fastening nut. If there is no electrical traces where the spring/nut has contact with the heat bed, it can be left out.

Consider that the hot bed gets "hot" and any plastic in contact with it can melt/soften - if replaced, select a material that can withstand the temperatures you will be using. I would recommend nylon.
It is just a small disk with a 1/8" (3-3.5mm) hole and can easily be made from an old credit card or similar...

Thanks. I only use PLA at present, so wondered whether the cups would be fine against the hotbed temperature wise.
To be on the safe side though, I'll source some Nylon washers. Thanks for the design though!

As I put this all back together, the thumbwheels would have to be a little less than 2x as thick to allow for the size of the M3 Nylock type nut. The current parts were made with a relatively well behaving Anet A8.
I am going to stretch the STL before I slice it and try for something a little deeper to house the locking nut for a second attempt.

This is really game-changer. Leveling is so much easier.
One warning: washers (in original configuration, springs) rest on heating pcb, protected only by solder mask. This could result in it cutting thin mask and short across heating element, potentially killing power supply or control board. I just used some cardboard between washer and bed, should be ok for PLA. Few layers of kapton would be better.

Thank you.
On all the PCB heatbeds I have seen, there is no active copper traces in the corners, only the solder mask. Compared to the original setup, the washer is protecting the heating layer from the sharp edges on the end of the spring.
In my opinion there is no danger of a short and the modification is safer than the original construction - if you want more isolation I would suggest using a nylon washer under the metal washer. Nylon will resist the heat when printing ABS (100C).

This was one of the best things I have done. There was a guy on Anets I was watching on youtube that drilled his bed screw out and raved about how much better it was. I actually had an issue where my thread got crossed on the bed screw and had no choice but to drill it out, best mod ever, never looked back. This one is a winner

Hi, nice upgrade ! I wish i had a drill right now :p
Other thing, what is the caramel colored tape/surface on the bed ? It looks like the adhesive around the cables on the extruder.
Is is working well ? I'm currently using the classic adhesive paper tape but i still have to heat up to 260 for the first ABS layer :/

Thank you.
The tape on the hotbed is Kapton tape - good for ABS print. I plan to replace it with a PEI sheet.
With ABS slurry it works well for ABS printing, but PEI can be used "as is" and works with a lot of other filament types.

Great mod, i'm doing this now. One suggestion, you can use M3 spring/lock washers instead of the nylon locking nuts to help lock the thumb screw from moving inadvertently. The M3 lock nuts are typically bigger height wise and may have problems sticking in your thumb wheel since they are a little thin. Overall great design, thanks!!

Thank you.
Depending on filament type and slicer used, the fit could be too tight.
Using heat to fit the nut is a great solution, as you did. Making the model 2-5% larger before print is another solution.

In this design the M3 screw is locked to the heat bed with a nut. For the bed leveling to work, the screw must be able to move freely through the threaded hole in the y carriage. Therefore the threading must be stripped with the drill (3mm or 1/8").

Thank you.
The pressure from the spring combined with the friction between y-carriage and thumbwheel should prevent the bed from "self adjusting".
But as you point out, the regular M3 nuts in the thumbwheel can be replaced with self locking M3 nuts (with nylon).

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